1. Field of the Invention
The present invention relates to a light control apparatus for a vehicle and, more particularly, to a light control apparatus for a vehicle which turns on lights for crime prevention purposes whenever the ignition switch is turned on and the engine is started.
2. Description of the Related Art
It is known in the prior art to provide a vehicle light control apparatus wherein, when the ignition switch or the accessory switch is turned on, and thereafter the switch is turned off while leaving the headlights and/or the sidemarker lights ON, the headlights and the sidemarker lights are kept turned on until the driver's side door is opened. It is also known to provide a vehicle light control apparatus which includes an automatic light ON/OFF unit for automatically turning on the headlights and the sidemarker lights when the ambient light level is low, and for automatically turning off the headlights and the sidemarker lights when the ambient light level is high.
In Japanese Patent No. 2983132, it is disclosed that, in such a vehicle light control apparatus, when stopping the engine after the engine was started by remote operation from outside the vehicle, a door open/close signal is transmitted to simulate the door open condition, thereby turning off the lights to prevent battery drain.
Japanese Unexamined Patent Publication No. H11-245712 discloses an automatic light control apparatus wherein provisions are made not to enable the automatic light control unless the key insertion switch is turned on, and thereby to prevent the battery from running low with the headlights left ON after the engine was started and subsequently stopped by a remote operation.
In a vehicle light control apparatus (hereinafter referred to as the “light control apparatus”), when the ambient light level is low, the lights must be turned on for crime prevention purposes whenever the ignition switch (hereinafter abbreviated “IG-SW”) is turned on and the engine is started. In such a light control apparatus, the lights need to be turned on when the IG-SW is turned on, whether it be turned on by key insertion or by a remote operation.
FIG. 1 is a diagram for explaining an example of an operation of such a light control apparatus. The example here deals with the case where the engine is started manually.
First, when the key is inserted to set the IG-SW on and the key is turned to activate the starter (S1), the engine starts (S2). At this point, the key insertion switch (hereinafter abbreviated “k-SW”) becomes ON. When the ambient light level is low, then the driver usually turns on the light switch manually to turn on the lights such as the sidemarker lights and the headlights (S3).
On the other hand, if the light control apparatus is equipped with an automatic light ON/OFF unit, the automatic light switch (hereinafter referred to as the “automatic light SW”) is set ON when the IG-SW is turned on. Then, if the ambient light sensor determines that the ambient light level is low, the lights such as the sidemarker lights and the headlights are automatically turned on (S4).
When the engine is stopped by turning off the IG-SW (S5), if the lights had been turned on manually, the lights remain ON. On the other hand, if the automatic light SW is ON, the lights remain ON if the ambient light level is low (S6). The lights will be turned off if, for example, one of the following three conditions is satisfied:                1) Vehicle door such as driver's side door is opened (S7);        2) Vehicle door such as driver's side door is opened, and then closed (S8);        3) Predetermined time has elapsed after opening and then closing vehicle door such as driver's side door (S9).Which condition to use can be determined appropriately. When the predetermined one of the three conditions is satisfied, the lights are turned off (S10). This prevents battery drain (S11).        
FIG. 2 is a diagram for explaining another example of operation of the light control apparatus. The example here deals with the case where the engine is started by turning on the IG-SW by such means as a remote operation.
Suppose, for example, that the lights were turned off by opening and then closing the door with the manual light SW left in the ON position; in this condition (the condition in S10 of FIG. 1), when the IG-SW is turned on (S1), the lights turn on (S3). Or, when the IG-SW is turned on, the automatic light SW becomes ON, and the lights turn on if the ambient light level is low (S3).
In this condition, if the IG-SW is turned off by transmitting an engine stop signal by remote operation from outside the vehicle (S4), the lights remain ON unless the prescribed condition, for example, the condition that the driver's side door is opened, is satisfied (S5). In this way, when the IG-SW is turned on or off by remote operation, as the driver's side door is not actually opened or closed, the lights remain ON, which drains the battery (S6). This can happen, for example, when warming up the engine by turning on and off the IG-SW by remote operation.